HS2 Water Orton viaducts mark a Delta junction milestone

HS2 Water Orton viaducts moved a step forward over the Christmas break, after engineers finished two key spans above the existing railway near Water Orton in Warwickshire, according to the HS2 Media Centre.

This is reported by the railway transport news portal Railway Supply.

Those spans make up a small but important element of the Delta junction HS2 is building to the east of Birmingham. The junction is laid out as a large triangle, formed by a complex network of interconnected viaducts that take the high-speed route over motorways, local roads, existing railways, rivers and floodplains. It is designed to carry HS2 services to and from Birmingham, while also tying into the main line heading north and south.

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To maintain speeds of 360km/h on the main line and around 200km/h on the approaches into Birmingham, the junction extends across a much larger area than a typical motorway interchange. Altogether, it spans 2.6 miles of track and includes underpasses, flyovers and five major viaducts.

At the northern end of the layout are the Water Orton viaducts. When they enter service, southbound trains will be able to join the Birmingham Curzon Street spur and continue to the Washwood Heath rolling stock depot.

Water Orton viaducts: spans placed above the Birmingham–Peterborough line

This latest milestone came during a five-day closure over the quieter Christmas period. Engineers working for HS2’s local main works contractor, Balfour Beatty VINCI (BBV), used that window to safely install the two parallel spans over the Birmingham to Peterborough railway line; the contractor also outlined the work in a Balfour Beatty project update. During the closure, buses replaced trains between Birmingham New Street and Coleshill.

Now that the railway crossing is complete, attention can turn to the next sections of the viaducts. The coming stages will take the structures over the nearby A446 road and the M42 motorway next year.

Sam Hinkley, HS2 Ltd’s Senior Project Manager, said: “It’s great to see the Water Orton viaducts in place across the railway and I’d like to thank everyone who gave up their Christmas to help us reach this important milestone and I’d like to thank passengers for their patience. These precast segmental viaducts form a key part of the Delta junction – one of the most complex parts of the HS2 project and I look forward to seeing more progress in the year ahead.”

Precast segmental viaducts and the cantilever construction method

Once complete, the two single-track Water Orton viaducts will extend for around 1.4km, crossing two railways as well as a river, local roads and the M42. They are being assembled from pre-cast concrete segments using a large cantilever process. After each span is in place, permanent post-tensioned cables are installed through the hollow centre of the viaduct, allowing the temporary cable stays to be moved forward to support assembly of the next span. The same sequence is repeated between each pier until all spans are finished.

The Water Orton viaducts stand on 32 concrete piers, up to 20m tall, cast in situ using bespoke formwork and reinforcing cages manufactured at nearby Coleshill. They form part of 3.7 miles worth of viaduct across Delta junction being built using the same approach. In total, 2,742 concrete segments for the viaducts are being manufactured at a temporary factory at nearby Lea Marston, as set out on HS2’s Water Orton Viaducts page.

Stephane Ciccolini, senior works manager at Balfour Beatty VINCI, said: “This complex section of the HS2 route has taken a major step forward, after BBV teams successfully erected two viaducts spans over an existing railway near Water Orton. We’ve worked around the clock during the Christmas period to deliver this incredible feat of engineering, using a specialist cantilever technique not seen in the UK before this project. This approach involves using a 22-metre-high mast and a 14-metre-high swivel crane to move each individual segment into place until the span is complete.”

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